The spectropolarimeter (JASCO Model J-600) requested in this proposal will be used to measure circular dichroism (CD) and magnetic circular dichroism (MCD) spectra in the investigation of the secondary structure, dynamics, and interactions of various proteins. The systems to be studied include human plasma apolipoproteins in solution and in lipid bound states, the electron transport enzymes of E. coli and Rhodobacter sphaeroides, putidaredoxin and cytochrome P450CAM from Pseudomonas putida, mammalian rhodopsin and transducin, and bacteriorhodopsin from Halobacterium halobium, and the lipid transfer protein from human plasma. The investigators contributing to this proposal come from several departments of the University of Illinois at Urbana-Champaign, including Biochemistry, Physics, Physiology and Biophysics, and Food Science. This broad based interest reflects the fact that there is not a single operational CD instrument available on this campus. This CD instrument will be maintained by the School of Chemical Sciences and will be located in the Laboratory for Fluorescence Dynamics (LFD).